Posi, good for icy roads?
I have lived in the NW pretty much all of my life, my first legally driven car was a 73 Camaro with a 327 that was pushing around 500hp with a 4 speed, a posi and a scary set of big and littles. I drove it in the snow and ice with no problems.
If your kid has a brain in his head he can handle a posi in the snow, not like it snows enough to worry about it here anyways. Just do what I do when it snows anymore, throw a set of studded snow tires on the dart and go!